Research On Routing Algorithm In Delay-Tolerant Mobile Sensor Networks

As the study of wireless sensor network goes deeper, more and more applications require the nodes in network partially or totally to be mobile such as the wildlife tracker network, underwater sensor network, etc. The topology of mobile sensor networks dynamically changes due to the mobility of nodes. Thus, there are no stable end-to-end delivery paths in such networks. As the traditional routing algorithms in wired networks or wireless ad hoc networks are based on the assumption that there are stable end-to-end delivery paths, they cannot work well in mobile sensor networks. Therefore, how to efficiently deliver messages in the network with dynamical topology is a significant problem that should prior be solved in mobile sensor networks.On the other hand, a novel concept, delay-tolerant network, arises in wireless network domain. It refers to those networks without stable end-to-end delivery paths, which cover the outer space network, village network, mobile sensor network, wireless ad hoc network, etc. By far, there have been many representative results in the research field of delay-tolerant network routing algorithm. As mobile sensor network just is a typical class of delay-tolerant networks, we can study the routing problem of mobile sensor network under the delay-tolerant network infrastructure. Therefore, we study the routing problem in delay-tolerant mobile sensor networks under the support of National 863 project and National Natural Science Foundation of China project.The concrete research content and creative contributions are presented as follows.1) As first, we investigate the routing problem in delay-tolerant mobile sensor network under a semi-determined mobility model. In such a network model, we assume that nodes have derived out their visiting probabilities to each network area in every time slot based on some prior knowledge or historical records. Then, we study the routing problem of single-copy message delivery in such a network, and propose an area-visiting-probability-based delay-tolerant mobile sensor network routing algorithm PROAREA so as to achieve the minimum delivery delay.The main creative contribution is introduced as follows. The previous probability-based delay-tolerant algorithms only utilize the idea that more the meeting probability, more the probability of successful delivery to qualitatively guide the routing selection. However, the PROAREA algorithm directly derives out the expected delivery delay between nodes from their meeting probability and utilizes it to quantitatively guide the routing selection. The experiment results show that compared with the previous algorithms, the PROHET algorithm selects the relay better so that it can increase the successful delivery rate and reduce the delivery delay.2) Furthermore, we investigate the routing problem in delay-tolerant mobile sensor network with limited transmission capacity. Suppose that the transmission capacity of nodes in the network. When the flow in the optimal delivery path is saturated, what a strategy should be adopted to decrease the total delivery delay, waiting or selecting other delivery path? This paper just studies this problem and proposes the PROAREA-LC algorithm.The main creative contribution is that this algorithm modeling the routing problem in delay-tolerant mobile sensor network with limited transmission capacity as a cost flow problem, and use the minimum-cost maximum flow algorithm to successfully solve this problem. The experiment results show that compared with the previous algorithms, the PROHET-LC algorithm can reduce the end-to-end delivery delay further.